Question

When will the bomb hit the submarine? If an aeroplane flying 1200m above water, observes a submarine 1800m below it.

mu_"water"=4/3

• 6sqrt(10)s
• 20sqrt(5)s
• 20s
• 15s

Solution

This a simple question we just need to understand that the submarine appears closer to the pilot than it actually is.

"Real depth"/"Apparent depth"=mu

In our case, the submarine appears to be at 600m below water level.

"Real depth"=4/3*600=800m

So the bomb has to travel a total of 2000m.

Time taken sqrt((2h)/g)=sqrt(400)=20m/s